class Dog():
	"""一次模拟小狗的简单尝试""" 

	def __init__(self, name, age):
		"""初始化属性name和age"""
		self.name = name
		self.age = age 

	def sit(self):
		"""模拟小狗被命令时蹲下"""
		print(self.name.title() + " is now sitting.") 

	def roll_over(self):
		"""模拟小狗被命令时打滚"""
		print(self.name.title() + " rolled over!")

#my_dog = Dog('willie', 6)
#my_dog.sit()
#my_dog.roll_over()
#print("My dog's name is " + my_dog.name.title() + ".")
#print("My dog is " + str(my_dog.age) + " years old.")

my_dog = Dog('willie', 6)
your_dog = Dog('lucy', 3) 

print("My dog's name is " + my_dog.name.title() + ".")
print("My dog is " + str(my_dog.age) + " years old.")
my_dog.sit()

print("\nYour dog's name is " + your_dog.name.title() + ".")
print("Your dog is " + str(your_dog.age) + " years old.")
your_dog.sit()